Reflection Phase Measurements for Ultrasonic NDE of Titanium Diffusion Bonds

The adoption of diffusion bonding in fracture critical titanium components has been limited by the complications that macroscopic anisotropy introduces to typical ultrasonic inspections. Previous attempts to overcome these limitations by using signal phase to extract otherwise hidden interface information showed promise but were susceptible to measurement error and proved impractical for typical aerospace component geometries. In the work presented here, significant improvements to the existing phase measurement approach are proposed alongside adaptations that permit its broader practical implementation. The principal parameters that affect the phase analysis of ultrasonic signals were investigated and their optimisation resulted in up to an order of magnitude improvement in phase measurement reliability, even at low signal-to-noise ratios. The application of these optimised parameters without a priori knowledge of the signal arrival time in an otherwise noisy waveform is illustrated, and the sensitivity of the approach to ambient temperature and annealing effects is also explored.